Date tree waste-based binary fibrous mix for moderate to severe loss control

ABSTRACT

A date tree fiber mix lost circulation material (LCM) is provided. The date tree fiber mix LCM may include includes date tree trunk fibers produced from date tree trunks and date tree leaf and leaf stem fibers produced from date tree leaves and leaf stems. The LCM include a mix of 30% by weight date tree trunk fibers and 70% date tree leaf and leaf stem fibers, 40% by weight date tree trunk fibers and 60% date tree leaf and leaf stem fibers, 50% by weight date tree trunk fibers and 50% date tree leaf and leaf stem fibers. Methods of lost circulation control using and manufacture of a date tree fiber mix LCM are also provided.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority from U.S. Provisional Application No. 62/436,211 filed Dec. 19, 2016, and titled “DATE TREE WASTE-BASED BINARY FIBROUS MIX FOR MODERATE TO SEVERE LOSS CONTROL.” For purposes of United States patent practice, this application incorporates the contents of the Provisional Application by reference in its entirety.

BACKGROUND Field of the Disclosure

The present disclosure generally relates to controlling lost circulation in a wellbore during drilling with a drilling fluid. More specifically, embodiments of the disclosure relate to a lost circulation material (LCM).

Description of the Related Art

Lost circulation is one of the frequent challenges encountered during drilling operations. Lost circulation can be encountered during any stage of operations and occurs when drilling fluid (such as drilling mud) pumped into a well returns partially or does not return to the surface. While some fluid loss is expected, excessive fluid loss is not desirable from a safety, an economical, or an environmental point of view. Lost circulation is associated with problems with well control, borehole instability, pipe sticking, unsuccessful production tests, poor hydrocarbon production after well completion, and formation damage due to plugging of pores and pore throats by mud particles. In extreme cases, lost circulation problems may force abandonment of a well.

Lost circulation can occur in various formations, such as naturally fractured formations, cavernous formations, and high permeable formations. Lost circulation can be categorized by the amount of fluid or mud lost as seepage type, moderate type, severe type, and total loss. The extent of the fluid loss and the ability to control the lost circulation with an LCM depends on the type of formation in which the lost circulation occurs. Formations with low permeability zones, that is, those with microscopic cracks and fissures, usually have seepage type lost circulation. Other formations may experience lost circulation if an improper mud weight is used while drilling.

SUMMARY

Lost circulation materials (LCMs) are used to mitigate the lost circulation by blocking the path of the drilling fluid (such as drilling mud) into the formation. The type of LCM used in a lost circulation situation depends on the extent of lost circulation and the type of formation. Different types of LCMs such as granular, fibrous and flaky materials are frequently used either alone or in combination to control loss of circulation. For example, fibrous LCMs may include cedar fibers, wood fibers, jute fibers, or synthetic fibers to control loss of circulation.

Costs incurred in loss circulation situations may be due to losses of drilling fluids, losses of production, and the costs of LCMs, including importation of LCMs to drilling locations. Additionally, lost circulation can cause environmental problems if drilling fluids or LCMs interact with the environment surrounding the reservoir. The manufacture, use, and disposal of some conventional LCMs may pose a risk to sensitive environments, such as marine environments because they are not biodegradable and can be toxic to marine life.

Embodiments of the disclosure include a date tree fiber mix LCM composition used to mitigate or prevent lost circulation in a well, as well as provide seepage control and minimize or prevent fluid loss. The fibers of the date tree fiber LCM may form a stack of interweaved fibers in the gap or mouth of fractures and other openings of a loss zone. The networked and interweaved fibers create a mat-like porous structure over the fractures or other openings that significantly reduces the size of the openings. The reduction in size of the fractures, pores, gaps, fissures, cracks, and other openings only allows the escape of the fluid phase of a drilling mud, not the whole mud in an active mud system or in an LCM pill. The infiltration and deposition of colloidal and other mud solids into and at the mat-like structure creates an effective barrier to prevent the loss of whole mud in the loss zone.

In one embodiment, a method to control lost circulation in a lost circulation zone in a wellbore is provided. The method includes introducing an altered drilling fluid into the wellbore such that the altered drilling fluid contacts the lost circulation zone and reduces a rate of lost circulation into the lost circulation zone. The altered drilling fluid includes a drilling fluid and a lost circulation material (LCM). The LCM includes a first plurality of fibers produced from date tree trunks and a second plurality of fibers produced from at least one of date tree leaves and date tree leaf stems. In some embodiments, the altered drilling fluid consists of the drilling fluid and the LCM. In some embodiments, the LCM consists of the plurality of fibers produced from date tree trunks and the plurality of fibers produced from at least one of date tree leaves and date tree leaf stems. In some embodiments, the first plurality of fibers are 30% by weight of the LCM and the second plurality of fibers are 70% by weight of the LCM. In some embodiments, the LCM has a concentration of at least 30 pounds-per-barrel (ppb) in the altered drilling fluid. In some embodiments, each of the first plurality of fibers produced from date tree trunks has a diameter in the range of 0.4 millimeters (mm) to about 0.8 mm. In some embodiments, each of the second plurality of fibers produced from at least one of date tree leaves and date tree leaf stems has a diameter in the range of 0.5 millimeters (mm) to about 1 mm. In some embodiments, the first plurality of fibers include a first plurality of untreated fibers and the second plurality of fibers produced include a second plurality of untreated fibers.

In another embodiment, an altered drilling fluid includes a drilling fluid and a lost circulation material (LCM). The LCM includes a first plurality of fibers produced from date tree trunks and a second plurality of fibers produced from at least one of date tree leaves and date tree leaf stems. In some embodiments, the LCM consists of the first plurality of fibers produced from date tree trunks and the second plurality of fibers produced from at least one of date tree leaves and date tree leaf stems. In some embodiments, the first plurality of fibers include 30% by weight of the LCM and the second plurality of fibers include 70% by weight of the LCM. In some embodiments, the LCM has a concentration of at least 30 pounds-per-barrel (ppb) in the altered drilling fluid. In some embodiments, each of the first plurality of fibers produced from date tree trunks has a diameter in the range of 0.4 millimeters (mm) to about 0.8 mm. In some embodiments, each of the second plurality of fibers produced from at least one of date tree leaves and date tree leaf stems has a diameter in the range of 0.5 millimeters (mm) to about 1 mm. In some embodiments, the first plurality of fibers include a first plurality of untreated fibers and the second plurality of fibers produced include a second plurality of untreated fibers.

In another embodiment, a lost circulation material (LCM) composition includes a first plurality of fibers produced from date tree trunks and a second plurality of fibers produced from at least one of date tree leaves and date tree leaf stems. In some embodiments, the LCM composition consists of the first plurality of fibers produced from date tree trunks and the second plurality of fibers produced from at least one of date tree leaves and date tree leaf stems. In some embodiments, the first plurality of fibers are 50% by weight of the LCM and the second plurality of fibers are 50% by weight of the LCM. In some embodiments, each of the first plurality of fibers produced from date tree trunks has a diameter in the range of 0.4 millimeters (mm) to about 0.8 mm. In some embodiments, each of the second plurality of fibers produced from at least one of date tree leaves and date tree leaf stems has a diameter in the range of 0.5 millimeters (mm) to about 1 mm. In some embodiments, the first plurality of fibers include a first plurality of untreated fibers and the second plurality of fibers produced include a second plurality of untreated fibers.

In some embodiments, a method of forming a lost circulation material (LCM) is provided. The method includes grinding date tree trunks to produce a first plurality of fibers and grinding date tree leaves, leaf stems, or a combination thereof to produce a second plurality of fibers. The method further includes mixing a first amount of the first plurality of fibers and the second amount of the second plurality of fibers to form the LCM. In some embodiments, the method includes washing the date tree trunks before grinding date tree trunks and washing the date tree leaves, leaf stems, or a combination thereof before grinding the date tree leaves, the leaf stems, or a combination thereof. In some embodiments, the method includes crushing the date tree trunks to produce the first plurality of fibers, such that the crushing is performed during the grinding and crushing the date tree leaves, leaf stems, or a combination thereof to produce the second plurality of fibers, such that the crushing is performed during the grinding. In some embodiments, the first amount of the first plurality of fibers are 30% by weight of the LCM and the second amount of the second plurality of fibers are 70% by weight of the LCM. In some embodiments each of the first plurality of fibers has a diameter in the range of 0.4 millimeters (mm) to about 0.8 mm. In some embodiments, each of the second plurality of fibers has a diameter in the range of 0.5 millimeters (mm) to about 1 mm.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a photograph of date tree trunks of date tree leaves and leaf stems from deceased date trees in accordance with an embodiment of the disclosure;

FIG. 2 is a photograph of date tree trunks from deceased date trees in accordance with an embodiment of the disclosure;

FIG. 3 is a schematic diagram illustrating a fiber network formed by fibers produced from date tree leaves and leaf stems;

FIG. 4 is a schematic diagram of a fiber network formed by the date tree leaf and leaf stem fibers and fibers produced from date tree trunks in accordance with an embodiment of the disclosure; and

FIG. 5 is a process for the production and use of a date tree fiber mix LCM in accordance with an embodiment of the disclosure.

DETAILED DESCRIPTION

The present disclosure will now be described more fully with reference to the accompanying drawings, which illustrate embodiments of the disclosure. This disclosure may, however, be embodied in many different forms and should not be construed as limited to the illustrated embodiments. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

As a wellbore is drilled, a drilling fluid is continuously pumped into the wellbore to clear and clean the wellbore and the filings. The drilling fluid is pumped from a mud pit into the wellbore and returns again to the surface. A lost circulation zone is encountered when the flow rate of the drilling fluid that returns to the surface is less than the flow rate of the drilling fluid pumped into the wellbore. It is this reduction or absence of returning drilling fluid that is referred to as lost circulation.

Embodiments of the disclosure include a date tree fiber mix LCM that includes a mix of date tree fibers obtained from date tree waste to mitigate or prevent lost circulation in a well, as well as provide seepage control and minimize or prevent fluid loss. As used in the disclosure, the term date tree waste refers to the waste produced from farming and processing date trees (also referred to as “date palms”), such as in the production of date fruits (also referred to as “dates”). In some embodiments, the date tree fiber mix LCM is a binary fiber mix that includes fibers formed from date tree trunks and fibers formed from date tree leaves and leaf stems.

FIG. 1 is a photograph 100 of date tree leaves and leaf stems from deceased date trees in accordance with an embodiment of the disclosure. As discussed in the disclosure, fibers manufactured from the date tree leaves and leaf stems may be relatively tough and inflexible as compared to the fibers manufactured from date tree trunks. FIG. 2 is a photograph 200 of date tree trunks from deceased date trees in accordance with an embodiment of the disclosure. As discussed in the disclosure, fibers manufactured from the date tree trunks may be relatively flexible, soft, bendable, and adaptable as compared to the fibers manufactured from date tree leaves and leaf stems

With the foregoing in mind, a date tree fiber mix LCM may, in some embodiments, include a binary fiber mix having fibers manufactured from date tree leaves and leaf stems and fibers manufactured from date tree trunks. In some embodiments, a date tree fiber mix LCM may include 30% by weight date tree trunk fibers and 70% by weight date tree leaf and leaf stem fibers. In some embodiments, the date tree fiber mix LCM may include 40% by weight date tree trunk fibers and 60% by weight date tree leaf and leaf stem fibers. In some embodiments, the date tree fiber mix LCM may include 50% by weight date tree trunk fibers and 50% by weight date tree leaf and leaf stem fibers.

In some embodiments, the date tree fiber mix LCM may include fibers having an aspect ratio in the range of about 5 to about 50. In some embodiments, the date tree trunk fibers may include fibers having the following distribution, as determined by the diameters of the fibers passed or retained in mesh openings: about 35% to about 55% of fibers passing through sieve mesh no. 10 and retained in sieve mesh no. 18, about 35% to about 55% of fibers passing through sieve mesh no. 18 and retained in sieve mesh no. 60, and about 5% to about 15% of fibers passing through sieve mesh no. 60 and retained in sieve mesh no. 200. In some embodiments, the date tree trunk fibers have diameters in the range of about 0.4 mm to about 0.8 mm with an average diameter of about 0.6 mm. In some embodiments, date tree leaf and leaf stem fibers may include fibers having the following distribution, as determined by the diameters of the fibers passed or retained in the mesh openings: about 55% to about 75% of fibers passing through sieve mesh no. 10 and retained in sieve mesh no. 18, about 15% to about 35% of fibers passing through sieve mesh no. 18 and retained in sieve mesh no. 60, and about 4% to about 16% of fibers passing through sieve mesh no. 60 and retained in sieve mesh no. 200. In some embodiments, the date tree leaf and leaf stem fibers have diameters in the range of about 0.5 mm to about 1 mm with an average diameter of about 0.75 mm.

The presence of two types of fibers with different physiomechanical properties may enable the date tree fiber mix LCM to form tightly packed plugs and seals in cracks and fractures in loss zones to provide improved control of the loss of whole mud from the borehole to the surrounding formation, as compared to conventional and existing fiber LCMs. For example, FIG. 3 is a schematic diagram illustrating a fiber network 300 formed by fibers manufactured from date tree leaves and leaf stems. The fiber network 300 illustrates a relatively larger mesh network formed by the relatively tough and inflexible date tree leaf and leaf stem fibers, as compared to more flexible fibers. In contrast, FIG. 4 is a schematic diagram of a fiber network formed by the date tree leaf and leaf stem fibers and fibers produced from date tree trunks in accordance with an embodiment of the disclosure. The fiber network 400 illustrates the interlacing and interweaving enabled by the relatively flexible date tree trunk fibers. The fiber network 400 may provide for the formation of tightly packed, rigid, low permeability and pressure tolerant plugs and seals within the fractures, gaps, fissures, cracks, faults and other openings of a formation to prevent the loss of whole mud during drilling or other operations. In some embodiments, the fiber network 400 may be capable of blocking fractures, gaps, fissures, cracks, faults and other openings having a size of 3 millimeters (mm) or less at their most narrow portion, such that the fiber network 400 can create a flow barrier to completely prevent whole mud losses or, in some instances, partially prevent whole mud losses, depending on the nature of subsurface loss zone. The combination of both types of fibers may improve the flow barrier properties of the date tree fiber mix LCM as compared to a single fiber LCM, due to the different physiomechanical properties of the each type of fiber in the mix. For example, the fiber network 400 may be a relatively finer mesh than a fiber network formed by a single fiber LCM. The fiber network may have improved mechanical strength, load bearing capacity, and pressure tolerance as compared to a single fiber LCM.

EXAMPLES

The following examples are included to demonstrate embodiments of the disclosure. It should be appreciated by those of skill in the art that the techniques and compositions disclosed in the example which follows represents techniques and compositions discovered to function well in the practice of the disclosure, and thus can be considered to constitute modes for its practice. However, those of skill in the art should, in light of the present disclosure, appreciate that many changes can be made in the specific embodiments which are disclosed and still obtain a like or a similar result without departing from the spirit and scope of the disclosure.

The following non-limiting examples of a date tree fiber mix LCM were prepared and evaluated against a commercially available LCM. Plugging efficiency tests were conducted on the date tree fiber mix LCM and a commercially available LCM using a 2 millimeter (mm) slotted disc and a Permeability Plugging Tester (also referred to as “PPT” or “Pore Plugging Test” apparatus) manufactured by OFI Testing Equipment, Inc., of Houston, Tex., USA. The tests were conducted at conditions of about 212° F. and about 1000 psi differential pressure. For the plugging efficiency tests, the date tree fiber mix LCM and commercially available LCMs were incorporated into a 65 pounds per cubic foot (pcf) bentonite mud. The composition of the 65 pcf bentonite mud with mud components expressed in pounds-per-barrels (lb/bbl) is shown in Table 1:

TABLE 1 Composition of 65 pcf bentonite mud Mud Component lb/bbl Water 340.67 Bentonite 25.00 Caustic Soda 0.25 Soda Ash 0.25

Three example formulations of a date tree fiber mix LCM were prepared and tested. The date tree trunk fibers used in the formulations had diameters in the range of about 0.4 mm to about 0.8 mm with an average diameter of about 0.6 mm. The date tree fibers used in the formulations had the following distribution, as determined by the diameters of the fibers passed or retained in mesh openings: about 35% to about 55% of fibers passing through sieve mesh no. 10 and retained in sieve mesh no. 18, about 35% to about 55% of fibers passing through sieve mesh no. 18 and retained in sieve mesh no. 60, and about 5% to about 15% of fibers passing through sieve mesh no. 60 and retained in sieve mesh no. 200. The date tree leaf and leaf stem fibers used in the formulations had diameters in the range of about 0.5 mm to about 1 mm with an average diameter of about 0.75 mm. The date tree leaf and leaf stem fibers used in the formulations had the following distribution, as determined by the diameters of the fibers passed or retained in the mesh openings: about 55% to about 75% of fibers passing through sieve mesh no. 10 and retained in sieve mesh no. 18, about 15% to about 35% of fibers passing through sieve mesh no. 18 and retained in sieve mesh no. 60, and about 4% to about 16% of fibers passing through sieve mesh no. 60 and retained in sieve mesh no. 200

A first formulation was prepared from 30% by weight date tree trunk fibers and 70% by weight date tree leaf and leaf stem fibers. A second formulation was prepared from 40% by weight date tree trunk fibers and 60% by weight date tree leaf and leaf stem fibers. A third formulation was prepared from 50% by weight date tree trunk fibers and 50% by weight date tree leaf and leaf stem fibers. The example formulations were evaluated to determine the improvement to the sealing and plugging capacity of the date tree trunk fibers provided by the various percentages of the date tree leaf and leaf stem fibers. The three example date tree fiber mix LCM formulations, a single fiber LCM formulation having 100% date tree trunk fibers, and a commercially available LCM were tested using the Permeability Plugging Tester apparatus and the following plugging efficiency test procedure:

1. Set the temperature controller/thermostat to the testing temperature;

2. Check the condition of the O-rings in the groove at the top of the test cell of the Permeability Plugging Tester apparatus and in the cell end cap and replace the O-rings if needed;

3. Apply a thin coating of high temperature grease to all the O-rings, including the two O-rings on the piston of the Permeability Plugging Tester apparatus;

4. Screw the T-bar of the Permeability Plugging Tester apparatus into the piston, install into the bottom end of the test cell, position the piston about 1 inch into the cell bore, and remove the T-bar;

5. Add a volume of hydraulic oil to the test cell using the hydraulic hand pump of the Permeability Plugging Tester apparatus;

6. Install all the O-rings and secure the end cap of the cell in position such that oil flows from the hole in the end cap to ensure no air is trapped;

7. Install the valve stem into the bottom end cap of the cell, tighten the valve stem, and disconnect from the hydraulic hand pump of the Permeability Plugging Tester apparatus;

8. Place the cell upright on a suitable stand;

9. Pour a test sample of a homogenous mixture of 275 ml of the 65 pcf bentonite mud and 30 grams of an LCM into the test cell;

10. Install an O-ring into the top of the cell below the 2 mm slotted disc;

11. Place the 2 mm slotted disc on top of the O-ring;

12. Insert the end cap on the top of the disc, screw down the threaded retaining ring, and fully tighten;

13. Tighten the top stem of the test cell;

14. Place the cell into the heating jacket of the Permeability Plugging Tester apparatus;

15. Connect a pressure hose from the hydraulic hand pump to the bottom of the test cell via a quick connector and ensure the bottom stem is closed;

16. Connect the back pressure hose/sample collector to the top stem of the test cell, ensuring that the locking pin is in place, close the pressure relief valve on the side of the hydraulic hand pump, apply the testing pressure via the back pressure regulator to the top of the test cell, and close the top valve.

17. Place a thermometer into the hole at the top of the test cell, wait until the testing temperature is reached, and monitor the cell pressure while heating and bleed off pressure if necessary by opening the pressure relived valve on the side of the hydraulic hand pump;

18. Once the test sample has reached the testing temperature, pump the hydraulic hand pump until the pump gauge shows the testing pressure plus the required back pressure;

19. Apply the required back pressure to the top of the cell, open the top valve, and pump the hydraulic hand pump to reestablish the testing pressure;

20. To determine the spurt volume, collect the fluid from the back pressure collector in a measuring cylinder and record the amount, ensuring that all the fluid has been expelled;

21. Collect the fluid periodically over a 30 minute time period and check the back pressure gauge to ensure that the pressure remains less than the pressure threshold (about 3000 psi) of the built-in safety disc of the Permeability Plugging Tester apparatus and avoid expulsion of hot hydraulic oil;

22. Record the spurt loss, total leak off, and PPT values over the 30 minute time period and record the cake thickness after dismantling the test cell.

The three formulations of the date tree fiber mix LCM were tested against a commercially available cellulosic fiber and flake LCM, STOPLOSS® manufactured by Drilchem of Jakarta, Indonesia. Table 2 shows the results of plugging efficiency tests for the single fiber LCM at 30 pounds-per-barrel (ppb) concentrations in the 65 pcf bentonite mud, the three example, formulations of the date tree fiber mix LCM at 30 ppb concentrations in the 65 pcf bentonite mud, and STOPLOSS® at a 30 ppb concentration in the 65 pcf bentonite mud, with the spurt loss, fluid loss, total leak off, and PPT value measured in cubic centimeters (cc) and the cake thickness measured in mm:

TABLE 2 Plugging Efficiency Test Results for Date tree fiber mix LCM and Commercially Available LCM Total Cake PPT Spurt Loss Fluid Loss Leak Off Thickness Value LCM Concentration (cc) (cc) (cc) (mm) (cc) 100% Date tree 30 ppb 2 30 32 6.32 64 trunk fibers 30% Date tree 30 ppb 1.3 9 10.3 22.2 20.6 trunk fibers: 70% date tree leaf and leaf stem fibers 40% Date tree 30 ppb 1 12 13 20.2 26 trunk fibers: 60% date tree leaf and leaf stem fibers 50% Date tree 30 ppb 1 16 17 17.7 34 trunk fibers: 50% date tree leaf and leaf stem fibers STOPLOSS ® 30 ppb 0.7 16 16.7 3.97 33.4

As shown in Table 2, the single fiber LCM having 100% date tree trunk fibers allowed significant fluid loss and failed to prevent fluid from escaping before sealing the slots of the disc in the PPT apparatus and stopping the loss of whole mud. The relatively flexible and bendable date tree trunk fibers of the single fiber LCM required a longer time to create an effective flow barrier in the disc slots. As also shown in Table 2, due to the relatively higher compressibility of the date tree trunk fibers, the resulting cake formed during the plugging efficiency tests was less thick than the cake formed by the three date tree fiber mix LCM formulations. The addition of the relatively strong and inflexible date tree leaf and leaf stem fibers in the example date tree fiber mix LCM formulations enable the quicker formation of an effective flow barrier in the slots of the PPT disc and thus significantly reduced fluid loss, as compared to the LCM having 100% date tree trunk fibers. Thus, the blending of date tree trunk fibers and date tree leaf and leaf stem fibers may improve the barrier-forming characteristics of the LCM formed from date tree fibers.

As shown in Table 2, each of the three date tree fiber mix LCM formulations exhibited reduced spurt loss and fluid loss as compared to the LCM having 100% date tree trunk fibers. Moreover, the total leak off decreased as the amount of date tree leaf and leaf stem fibers increases, thus further demonstrating the technical improvement to the LCM of the addition of the date tree leaf and leaf stem fibers.

As further shown in Table 2, the 30:70 and 40:60 date tree fiber mix LCM formulations showed superior performance as compared to the STOPLOSS® commercially available LCM. The 30:70 and 40:60 date tree fiber mix LCM exhibited reduced fluid loss, reduced total leak off, and formed a thicker cake than the STOPLOSS® commercially available LCM. As also shown in Table 2, the 50:50 date tree fiber mix LCM formulation showed comparable performance to the STOPLOSS® commercially available LCM. Thus, all three tree waste fiber mix LCM formulations may be viable alternatives to commercially available LCMs. As shown by the negligible spurt loss, negligible fluid loss, and negligible leak off, the 30 ppb concentrations of the example date tree fiber mix LCM formulations demonstrated the ability to seal a potential loss zone quickly with a negligible loss of whole mud into the loss zone under a 1000 psi differential pressure.

Date Tree Fiber Mix LCM Manufacture and Use

In some embodiments, a date tree fiber mix LCM may include date tree trunk fibers and a date tree leaf and leaf stem fibers. The date tree trunk fibers include fibers manufactured from date tree trunks, and the date tree leaf and leaf stem fibers include fibers manufactured from date tree leaves and leaf stems. The date tree trunks and date tree leaves and leaf stems may be obtained from date tree waste produced as a waste by-product from date tree farming and date processing. The date tree waste may be obtained from pruning waste and date processing plants to provide a sustainable source of material for the date tree fiber mix LCM. Moreover, local sources of date tree waste may reduce the cost of imported LCM products, components, or both. In some embodiments, the date tree trunks and date tree leaves and leaf stems may be obtained from the species phoenix daciylifera. It should be appreciated that, in some embodiments, the date tree trunks and date tree leaves and leaf stems may be obtained from genetically modified date trees (that is, genetically modified organisms (GMOs)). In some embodiments, the date tree trunks and date tree leaves and leaf stems may be prepared by cleaning the date tree trunks and date tree leaves and leaf stems before use or processing, such as by washing the date tree trunks and date tree leaves and leaf stems.

In some embodiments, the date tree trunk fibers may include fibers having the following distribution, as determined by the diameters of the fibers passed or retained in mesh openings: about 35% to about 55% of fibers passing through sieve mesh no. 10 and retained in sieve mesh no. 18, about 35% to about 55% of fibers passing through sieve mesh no. 18 and retained in sieve mesh no. 60, and about 5% to about 15% of fibers passing through sieve mesh no. 60 and retained in sieve mesh no. 200. In some embodiments, the date tree trunk fibers have diameters in the range of about 0.4 mm to about 0.8 mm with an average diameter of about 0.6 mm. In some embodiments, date tree leaf and leaf stem fibers may include fibers having the following distribution, as determined by the diameters of the fibers passed or retained in mesh openings: about 55% to about 75% of fibers passing through sieve mesh no. 10 and retained in sieve mesh no. 18, about 15% to about 35% of fibers passing through sieve mesh no. 18 and retained in sieve mesh no. 60, and about 4% to about 16% of fibers passing through sieve mesh no. 60 and retained in sieve mesh no. 200. In some embodiments, the date tree leaf and leaf stem fibers have diameters in the range of about 0.5 mm to about 1 mm with an average diameter of about 0.75 mm.

In some embodiments, the date tree fiber mix LCM is a binary mix of date tree trunk fibers and a date tree leaf and leaf stem fibers. In some embodiments, the date tree fiber mix LCM may include 30% by weight date tree trunk fibers and 70% by weight date tree leaf and leaf stem fibers. In some embodiments, the date tree fiber mix LCM may include 40% by weight date tree trunk fibers and 60% by weight date tree leaf and leaf stem fibers. In some embodiments, the date tree fiber mix LCM may include 50% by weight date tree trunk fibers and 50% by weight date tree leaf and leaf stem fibers. In other embodiments, the date tree fiber mix LCM may include 10% by weight or greater date tree trunk fibers and 90% by weight or less date tree leaf and leaf stem fibers, 20% by weight or greater date tree trunk fibers and 80% by weight or less date tree leaf and leaf stem fibers, 60% by weight or greater date tree trunk fibers and 40% by weight or less date tree leaf and leaf stem fibers, 70% by weight or greater date tree trunk fibers and 30% by weight or less date tree leaf and leaf stem fibers, 80% by weight or greater date tree trunk fibers and 30% by weight or less date tree leaf and leaf stem fibers, or 90% by weight or greater date tree trunk fibers and 10% by weight or less date tree leaf and leaf stem fibers.

In some embodiments, the date tree trunks may include untreated date tree trunks, and the date tree leaf and leaf stems may include untreated leaves and leaf stems, thus preserving the environmentally-friendly and biodegradable properties of the manufacturing process, the date tree trunk fibers and the date tree leaf and leaf stem fibers, and the resulting LCM composition. As used in the disclosure, the term “untreated” or “without treating” refers to not treated with alkali or acid, not bleached, not chemically altered, not oxidized, and without any extraction or reaction process other than possibly drying of water. The term “untreated” or “without treatments” does not encompass grinding or heating to remove moisture but does encompass chemical or other processes that may change the characteristics or properties of the fibers. In such embodiments, the date tree trunk fibers and date tree leaf and leaf stem fibers may be manufactured without treating before, during, or after crushing, grinding, drying, or any other processing.

In some embodiments, the date tree fiber mix LCM may be added directly to a drilling fluid, such as a drilling mud, to create an altered drilling fluid having the date tree fiber mix LCM. For example, in some embodiments, the date tree fiber mix LCM may be added to (for example, blended with) an oil-based drilling mud or a water-based drilling mud. In some embodiments, the date tree fiber mix LCM may be added at the mud pit of a mud system. After addition of the date tree fiber mix LCM to a drilling fluid, the altered drilling fluid may be circulated at a pump rate effective to position the altered drilling fluid into contact with a lost circulation zone in a wellbore, such that the date tree fiber mix LCM alters the lost circulation zone (for example, by entering and blocking porous and permeable paths, cracks, and fractures in a formation in the lost circulation zone, such as forming a structure in a mouth or within a fracture).

As noted in the disclosure, the properties of the date tree fiber mix LCM may prevent degradation of the date tree fiber mix LCM while circulating downhole as a fluid loss additive or formation strengthening material. Moreover, the eco-friendly, non-toxic, and environmentally friendly properties of the fibers of the date tree fiber mix LCM may minimize or prevent any environmental impact and effect on ecosystems, habitats, population, crops, and plants at or surrounding the drilling site where the date tree fiber mix LCM is used.

FIG. 5 depicts a process 500 for the production and use of a date tree fiber mix LCM in accordance with an example embodiment of the disclosure. As shown in FIG. 5, date tree leaves and leaf stems may be collected (block 502), such as from a date tree pruning waste produced by date tree farming and date processing industries. For example, date tree pruning may be performed at regular intervals (for example, yearly), resulting in a regular collection of date tree pruning waste. In some embodiments the date tree leaves and leaf stems may be cleaned, such as by a high pressure water or air jet, to remove dirt, dust, and other foreign substances. The collected date tree leaves and leaf stems may be crushed and ground to produce fibers from the date tree leaves and leaf stems (block 504). In some embodiments, the collected date tree leaves and leaf stems may be crushed and ground using a suitable commercial grinder that produces a specific range of fiber sizes (for example, length and diameter).

As also shown in FIG. 5, deceased date tree trunks may be collected, such as from date tree waste produced at a date processing facility (block 506). In some embodiments, date tree waste may be collected from a date processing facility and transported to another facility for processing as described in the disclosure. In some embodiments the date tree trunks may be cleaned, such as by a high pressure water or air jet, to remove dirt, dust, and other foreign substances. The collected date tree trunks may be crushed and ground to produce fibers from the date tree trunks (block 508). In some embodiments, the collected date tree trunks may be crushed and ground using a suitable commercial grinder that produces a specific range of fiber sizes (for example, length and diameter).

The date tree leaf and leaf stem fibers and the date tree trunk fibers may then be mixed to form a date tree fiber mix LCM having both fibers (block 510). In some embodiments, the mix of date tree leaf and leaf stem fibers and the date tree trunk fibers may be dried and packed for transportation and use (block 512). For example, the date tree leaf and leaf stem fibers and the date tree trunk fibers may be packed in water-proof bags containing about 25 kilograms (kg) of the mixed fibers. In some embodiments, the date tree leaf and leaf stem fibers and the date tree trunk fibers may be dried using a sun drying process over a time period in atmospheric conditions. In some embodiments, a suitable amount of packed mixed fibers may then be transported to an oil and gas operations site for use as a date tree fiber mix LCM.

In some embodiments, the date tree fiber mix LCM may be added directly to a drilling fluid (block 514), such as a drilling mud, to create an altered drilling fluid having the date tree fiber mix LCM. For example, in some embodiments, the date tree fiber mix LCM may be added to (for example, blended with) an oil-based drilling mud or a water-based drilling mud. In some embodiments, the date tree fiber mix LCM may be added at the mud pit of a mud system. After addition of the date tree fiber mix LCM to a drilling fluid, the altered drilling fluid may be circulated at a pump rate effective to position the drilling fluid into contact with a lost circulation zone in a wellbore, such that the date tree fiber mix LCM alters the lost circulation zone (for example, by entering and blocking porous and permeable paths, cracks, and fractures in a formation in the lost circulation zone). As previously stated, the date tree fiber mix LCM may form a fiber network at openings of paths, cracks, and fractures in a loss zone. In some embodiments, the reduced rate of lost circulation may be negligible. In some embodiments, the date tree fiber mix LCM may be introduced via an open ended drill pipe to place the LCM in the lost circulation zone

In other embodiments, the date tree fiber mix LCM and one or more additional LCMs may be added to a drilling fluid, such as a drilling mud, to create an altered drilling fluid having the LCMs. For example, in some embodiments, the date tree fiber mix LCM and one or more additional LCMs may be added to an oil-based drilling mud or a water-based drilling mud. In other embodiments, the date tree fiber mix LCM may be added to a cement slurry for use in a cementing operation.

The biodegradation properties of the date tree leaf and leaf stem fibers and the date tree trunk fibers of the date tree fiber mix LCM may enable the date tree fiber mix LCM to easily degrade and disappear from the environment over time and minimize or prevent any environmental impact. Further, the non-toxic properties of the date tree fibers may minimize or prevent any effect on ecosystems, habitats, population, crops, and plants surrounding the drilling site where the date tree fiber mix LCM is used.

In some embodiments, the date tree fiber mix LCM may be mixed with a carrier fluid, a viscosifier, or both. In some embodiments, a date tree fiber mix LCM homogenous suspension or pill may be formed. For example, a specific carrier fluid, viscosifier, or combination thereof may be selected to form a homogenous suspension or pill having the date tree fiber mix LCM. The homogenous suspension or pill may be added to a drilling fluid and used in the manner similar to the date tree fiber mix LCM described in the disclosure.

Ranges may be expressed in the disclosure as from about one particular value, to about another particular value, or both. When such a range is expressed, it is to be understood that another embodiment is from the one particular value, to the other particular value, or both, along with all combinations within said range.

Further modifications and alternative embodiments of various aspects of the disclosure will be apparent to those skilled in the art in view of this description. Accordingly, this description is to be construed as illustrative only and is for the purpose of teaching those skilled in the art the general manner of carrying out the embodiments described in the disclosure. It is to be understood that the forms shown and described in the disclosure are to be taken as examples of embodiments. Elements and materials may be substituted for those illustrated and described in the disclosure, parts and processes may be reversed or omitted, and certain features may be utilized independently, all as would be apparent to one skilled in the art after having the benefit of this description. Changes may be made in the elements described in the disclosure without departing from the spirit and scope of the disclosure as described in the following claims. Headings used described in the disclosure are for organizational purposes only and are not meant to be used to limit the scope of the description. 

What is claimed is:
 1. A method to control lost circulation in a lost circulation zone in a wellbore, comprising: introducing an altered drilling fluid into the wellbore such that the altered drilling fluid contacts the lost circulation zone and reduces a rate of lost circulation into the lost circulation zone, where the altered drilling fluid comprises a drilling fluid and a lost circulation material (LCM), wherein the LCM consists of: a first plurality of fibers produced from date tree trunks, wherein each of the first plurality of fibers has a diameter in the range of 0.4 millimeters (mm) to about 0.8 mm; and a second plurality of fibers produced from at least one of date tree leaves and date tree leaf stems, wherein each of the second plurality of fibers has a diameter in the range of 0.5 millimeters (mm) to about 1 mm; wherein the first plurality of fibers comprise 30% by weight of the LCM and the second plurality of fibers comprise 70% by weight of the LCM.
 2. The method of claim 1, wherein the altered drilling fluid consists of the drilling fluid and the LCM.
 3. The method of claim 1, wherein the LCM comprises a concentration of at least 30 pounds-per-barrel (ppb) in the altered drilling fluid.
 4. The method of claim 1, wherein the first plurality of fibers comprise a first plurality of untreated fibers and the second plurality of fibers produced comprise a second plurality of untreated fibers. 